Analyte sensor configuration and calibration based on data collected from a previously used analyte sensor

ABSTRACT

A method of automatically initializing an analyte sensor for a user is disclosed here. A first analyte sensor is operated in a first measurement mode to generate first sensor signals indicative of an analyte level of the user. A second analyte sensor is deployed to measure the analyte level of the user, and is operated in an initialization mode, concurrently with operation of the first analyte sensor in the first measurement mode, to receive sensor configuration data generated by the first analyte sensor. During operation of the second analyte sensor in the initialization mode, the second analyte sensor is calibrated with at least some of the received sensor configuration data. After the calibrating, operation of the second analyte sensor is transitioned from the initialization mode to a second measurement mode during which the second analyte sensor generates second sensor signals indicative of the analyte level of the user.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally toan analyte sensor for monitoring a physiological characteristic of auser, such as blood glucose level. More particularly, the disclosedsubject matter relates to an analyte sensor device and related operatingmethodologies for initializing and calibrating the analyte sensor devicewhen newly deployed.

BACKGROUND

The prior art includes a wide variety of medical devices and components,and associated operating methodologies. For example, physiologicalanalyte sensors are generally known in the art for use in a variety ofspecialized applications. In this regard, thin film electrochemicalsensors are used to test analyte levels in patients. More specifically,thin film sensors have been designed for use in obtaining an indicationof blood glucose (BG) levels and monitoring BG levels in a diabeticpatient, with the distal segment portion of the sensor positionedsubcutaneously in direct contact with patient extracellular fluid. Suchreadings can be especially useful in adjusting a treatment regimen whichtypically includes regular administration of insulin to the patient.

Conventional glucose sensor sets typically include three maincomponents: a disposable sensor with its mounting base; a durable,rechargeable transmitting device that is coupled to cooperate with thesensor; and a sensor insertion tool. The sensor component must bereplaced on a regular basis, usually about once a week, once every tendays, or the like. When the sensor component is replaced, the usersuspends any continuous glucose monitoring to recharge the transmittingdevice and to prepare the new sensor component for use. The sensorinsertion process is often long and complex. In some scenarios, the usermay have to wait over an hour before the new sensor is ready to provideglucose readings, which results in a break of the monitoring process.Moreover, newly deployed glucose sensors must be calibrated against areliable blood glucose measurement baseline, e.g., a fingerstick bloodsample or an accurate and trusted glucose sensor reading.

Accordingly, it is desirable to provide an improved analyte sensordevice and more convenient and efficient sensor deployment methodologiesthat make it easier and less time consuming to deploy and use a newsensor that replaces an old sensor. Furthermore, other desirablefeatures and characteristics will become apparent from the subsequentdetailed description and the appended claims, taken in conjunction withthe accompanying drawings and the foregoing technical field andbackground.

BRIEF SUMMARY

Disclosed here is a method of automatically initializing an analytesensor for a user. An exemplary embodiment of the method involves thesteps of: operating a first analyte sensor in a first measurement modeto generate first sensor signals indicative of an analyte level of theuser; deploying a second analyte sensor to measure the analyte level ofthe user; operating the second analyte sensor in an initialization mode,concurrently with operation of the first analyte sensor in the firstmeasurement mode, to receive sensor configuration data generated by thefirst analyte sensor; during operation of the second analyte sensor inthe initialization mode, calibrating the second analyte sensor with atleast some of the received sensor configuration data; and after thecalibrating, transitioning operation of the second analyte sensor fromthe initialization mode to a second measurement mode during which thesecond analyte sensor generates second sensor signals indicative of theanalyte level of the user.

Also disclosed here is an analyte sensor device. An exemplary embodimentof the sensor device includes: a housing; an electronics assembly insidethe housing; and a sensor element extending from the housing andelectrically coupled to the electronics assembly, wherein the sensorelement provides sensor signals indicative of an analyte level of a userwhen the analyte sensor device is deployed at the user. The electronicsassembly includes at least one processor device and non-transitoryprocessor-readable media operatively associated with the at least oneprocessor device. The processor-readable media stores executableinstructions configurable to cause the at least one processor device toperform a method that involves the steps of: activating aninitialization mode of the analyte sensor device; during operation ofthe analyte sensor device in the initialization mode, receiving sensorconfiguration data for processing by the electronics assembly, thesensor configuration data originating at a second analyte sensor devicedeployed at, or previously deployed at, the user; during operation ofthe analyte sensor device in the initialization mode, configuring atleast one sensor parameter of the analyte sensor device, based on thereceived sensor configuration data; and after the configuring,transitioning operation of the analyte sensor device from theinitialization mode to a measurement mode during which the analytesensor device generates sensor signals indicative of the analyte levelof the user.

Also disclosed here is another method of automatically initializing ananalyte sensor for a user. An exemplary embodiment of the methodinvolves the steps of: activating a new analyte sensor to measure ananalyte level of the user; during operation of the new analyte sensor inan initialization mode, receiving sensor configuration data at the newanalyte sensor, the sensor configuration data originating at an oldanalyte sensor deployed at, or previously deployed at, the user; duringoperation of the new analyte sensor in the initialization mode,configuring at least one sensor parameter of the new analyte sensor,based on the received sensor configuration data; and after theconfiguring, transitioning operation of the new analyte sensor from theinitialization mode to a first measurement mode during which the newanalyte sensor generates first sensor signals indicative of the analytelevel of the user.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the subject matter may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures.

FIG. 1 is a simplified block diagram representation of a medical devicesystem that is configured, arranged, and operated in accordance with anexemplary embodiment of the invention;

FIG. 2 is a perspective top view of an exemplary embodiment of ananalyte sensor device;

FIG. 3 is a side view of the analyte sensor device shown in FIG. 2;

FIG. 4 is a simplified block diagram representation of an exemplaryembodiment of a computer-based or processor-based device suitable fordeployment in the system shown in FIG. 1;

FIG. 5 is a flow chart that illustrates an exemplary embodiment of asensor initializing and calibration process;

FIG. 6 is a block diagram that illustrates a device key managementscheme; and

FIG. 7 is a block diagram that illustrates a sensor pre-calibrationscheme.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary or the following detailed description.

Techniques and technologies may be described herein in terms offunctional and/or logical block components, and with reference tosymbolic representations of operations, processing tasks, and functionsthat may be performed by various computing components or devices. Suchoperations, tasks, and functions are sometimes referred to as beingcomputer-executed, computerized, software-implemented, orcomputer-implemented. It should be appreciated that the various blockcomponents shown in the figures may be realized by any number ofhardware, software, and/or firmware components configured to perform thespecified functions. For example, an embodiment of a system or acomponent may employ various integrated circuit components, e.g., memoryelements, digital signal processing elements, logic elements, look-uptables, or the like, which may carry out a variety of functions underthe control of one or more microprocessors or other control devices.

When implemented in software or firmware, various elements of thesystems described herein are essentially the code segments orinstructions that perform the various tasks. In certain embodiments, theprogram or code segments are stored in a tangible processor-readablemedium, which may include any medium that can store or transferinformation. Examples of a non-transitory and processor-readable mediuminclude an electronic circuit, a semiconductor memory device, a ROM, aflash memory, an erasable ROM (EROM), a floppy diskette, a CD-ROM, anoptical disk, a hard disk, or the like.

The subject matter described here relates to a physiological analytesensor device and related operating methodologies. The non-limitingexemplary embodiment described below relates to a continuous glucosesensor of the type used by diabetic patients. It should be appreciatedthat the concepts, operating methodologies, and calibration techniquesmentioned here need not be limited to use with glucose sensors and,indeed, the concepts and technology described with reference to aglucose sensor could also be used with other medical devices, otherphysiological characteristic sensor types, other medical components orsupplies, and the like.

For the sake of brevity, conventional aspects and technology related toglucose sensors and glucose sensor fabrication may not be described indetail here. A glucose sensor of the type described here may be realizedas an electrochemical sensor that employs the glucose oxidase enzyme.Sensors that use glucose oxidase to effect a reaction of glucose andoxygen are known, and such glucose sensors will not be described indetail here. In this regard, known and/or conventional aspects ofglucose sensors and their manufacturing may be of the type described in,but not limited to: U.S. Pat. Nos. 5,391,250, 6,892,085, 7,468,033, and7,602,310, and United States patent application numbers 2009/0299301 and2017/0290535 (which are incorporated by reference herein).

FIG. 1 is a simplified block diagram representation of a medical devicesystem 100 that is configured, arranged, and operated in accordance withan exemplary embodiment of the invention. The system 100 supports a user102 of a medical device 104 that regulates the delivery oradministration of medication to the user 102. Although not alwaysrequired, the medical device 104 may include or cooperate with a therapydelivery unit 106 that is attached to, worn by, or implanted in the bodyof the user 102 to facilitate the delivery of the medication to the user102. The medical device 104 includes or cooperates with an analytesensor device, which measures an analyte level of the user 102. Inpractice, the analyte sensor device is a disposable component that mustbe replaced on a regular basis. Accordingly, FIG. 1 depicts an oldanalyte sensor device 108 (a first analyte sensor) and a new analytesensor device 110 (a second analyte sensor), wherein the new analytesensor device 110 replaces the old analyte sensor device 108 at anappropriate time. The embodiment of the system 100 shown in FIG. 1 alsoincludes or cooperates with an intermediary device 112 having one ormore software applications that support the techniques and methodologiesdescribed in more detail herein. The intermediary device 112 can berealized as a mobile computing device, a smartphone, a patient monitordevice, a wearable computing device such as a smart watch, a video gamedevice, a media player device, a medical device, or the like. In someimplementations, the system 100 need not include the intermediary device112 if the medical device 104 includes the features and functions of theintermediary device 112. In other words, the medical device 104 may alsoserve as the intermediary device.

In accordance with the non-limiting example described here, the medicaldevice 104 is realized as a medication infusion device configured toregulate delivery of a medication fluid to the user 102, wherein thetherapy delivery unit 106 is realized as a fluid infusion unit having afluid delivery cannula or needle that is deployed in the skin or body ofthe user 102. The medical device 104 regulates delivery of themedication to the user based on sensor signals provided by the analytesensor device(s). In certain embodiments, the medical device 104 is aninsulin infusion device, the therapy delivery unit 106 is adisposable/replaceable insulin infusion set that is fluidly coupled tothe insulin infusion device, and the analyte sensor devices 108, 110 arecontinuous glucose sensor devices. In this context, the insulin infusiondevice, the glucose sensor devices, and the infusion set are componentsof an insulin infusion system that is used by the patient to treatdiabetes.

At least some of the components of the system 100 are communicativelycoupled with one another to support data communication as needed. Forthis particular example, the medical device 104 can wirelesslycommunicate with the analyte sensor devices 108, 110 via suitable datacommunication links and communication protocols. Moreover, theintermediary device 112 can wirelessly communicate with the analytesensor devices 108, 110 via suitable data communication links andcommunication protocols. In certain embodiments, the analyte sensordevices 108, 110 can wirelessly communicate directly with each other viaa suitable data communication link and communication protocol. Otherconfigurations and topologies are also contemplated here, such as asystem that includes additional intermediary, interface, or datarepeating devices in the data path between a sending device and areceiving device.

Depending on the particular embodiment and application, the system 100can include or cooperate with other devices, systems, and sources ofinput data. For example, in certain embodiments the system 100 includesone or more sources of contextual information or data, which mayinclude, without limitation: activity tracker devices or apps; meallogging devices or apps; mood tracking devices or apps; and the like.

FIG. 1 depicts network communication links in a simplified manner. Inpractice, the system 100 may cooperate with and leverage any number ofwireless and any number of wired data communication networks maintainedor operated by various entities and providers. Accordingly,communication between the various components of the system 100 mayinvolve multiple network links and different data communicationprotocols. In this regard, the network can include or cooperate with anyof the following, without limitation: a local area network; a wide areanetwork; the Internet; a personal area network; a near-field datacommunication link; a cellular communication network; a satellitecommunication network; a video services or television broadcastingnetwork; a network onboard a vehicle; or the like. The components of thesystem 100 may be suitably configured to support a variety of wirelessand wired data communication protocols, technologies, and techniques asneeded for compatibility with the network.

FIG. 2 is a perspective top view of an exemplary embodiment of ananalyte sensor device 200 (which is suitable for use in the medicaldevice system 100), and FIG. 3 is a side view of the analyte sensordevice 200. The illustrated embodiment of the analyte sensor device 200includes a housing 202 having an upper housing 204 with an upper majorwall inside the upper housing 204, and a lower housing 206 with a lowermajor wall inside the lower housing 206, where the upper and lower majorwalls oppose each other. The housing 202 is shown as generallyrectangular, but other shapes, such as square shapes, circular shapes,and polygon shapes, can be used according to the size of the componentshoused inside and to increase comfort levels on the skin. The housing202 has a low profile to decrease visibility through clothing and alsoto decrease discomfort and interference from the sensing device when itis worn on a patient's skin.

The housing 202 may be attached to an adhesive patch 210 for press-onadhesive mounting onto the skin of the user. The patch 210 may be sizedsuch that it has as much adhesion to skin as possible while not beingtoo large for comfort or to easily fit on a patient. It should beappreciated that alternative methods or techniques for attaching thehousing 202 to the skin of a patient, other than an adhesive patch 210,also may be contemplated. The housing 202 may be made out of a suitablerigid plastic that can safely and securely hold electrical components ofthe analyte sensor device 200. In this configuration, the upper housing204 includes a small opening 212 for pass through of a battery pull tab(not shown) used to block an internal battery from contacting theelectronic battery contacts prior to use, thus preventing batterydepletion and preventing premature activation of the analyte sensordevice. In certain embodiments, removal of the pull tab causes thesensor device 200 to activate or enter an initialization mode (asdescribed in more detail below).

The adhesive patch 210 may be bonded to the lower housing 206 along theentire footprint of the lower housing 206, or over just a portion, suchas the perimeter of the lower housing 206. The patch 210 may beultrasonically welded to the lower housing 206 or adhered, for example,by a double-sided adhesive. In certain configurations, the adhesivepatch 210 extends further than the edge of the lower housing 206.

FIG. 3 shows a side view of the analyte sensor device 200 with a thinfilm sensor element 220 extending from the housing 202 and through thepatch 210, which may include a hole for the sensor element 220 to passthrough. As shown in FIG. 3, the sensor element 220 includes arelatively thin and elongated element which can be constructed accordingto so-called thin mask techniques to include elongated conductiveelements embedded or encased between layers of a selected insulativesheet material such as a polyimide film or sheet. The proximal end orhead of the sensor element 220 is relatively enlarged and defineselectrical contacts for electrical coupling to an electronics assembly224 (depicted in phantom lines in FIG. 3) that resides inside thehousing 202. An opposite or distal segment of the sensor element 220includes a plurality of exposed sensor electrodes that contact bodyfluid and/or tissue when the sensor distal segment is placed into thebody of the user. The sensor electrodes convey sensor signalsrepresentative of the measured analyte level of interest. Thus, thesensor element 220 provides sensor signals that are indicative of theanalyte level of the user when the analyte sensor device 200 is deployedat the user.

The sensor signals are transmitted in an ongoing manner from the analytesensor device 200 (which includes a wireless transmitter) to anappropriate destination device for recordation, processing, and/ordisplay as a monitored patient condition. Referring again to FIG. 1, theanalyte sensor device 200 may be suitably configured to transmit sensorsignals to the medical device 104, to the intermediary device 112,and/or to another sensor device. Further description of flexible thinfilm sensors of this general type may be found in U.S. Pat. No.5,391,250, which is herein incorporated by reference. Sensor electronicsincluding wireless transmitters are discussed, for example, in U.S. Pat.No. 7,602,310, which is herein incorporated by reference.

In accordance with certain embodiments, the medical device 104, theintermediary device 112, and each analyte sensor device 108, 110 can beimplemented as a computer-based or a processor-based device, system, orcomponent having suitably configured hardware and software written toperform the functions and methods needed to support the featuresdescribed herein. In this regard, FIG. 4 is a simplified block diagramrepresentation of an exemplary embodiment of a computer-based orprocessor-based device 400 that is suitable for deployment in the systemshown in FIG. 1.

The illustrated embodiment of the device 400 is intended to be ahigh-level and generic representation of one suitable platform. In thisregard, any computer-based or processor-based component of the system100 can utilize the architecture of the device 400. The illustratedembodiment of the device 400 generally includes, without limitation: atleast one processor device 402; a suitable amount of memory 404;device-specific hardware, software, firmware, user interface (UI),and/or features 406; a power supply 408 such as a disposable orrechargeable battery; a communication module 410; and a display element412. Of course, an implementation of the device 400 may includeadditional elements, components, modules, and functionality configuredto support various features that are unrelated to the subject matterdescribed here. For example, the device 400 may include certain featuresand elements to support conventional functions that might be related tothe particular implementation and deployment of the device 400. Inpractice, the elements of the device 400 may be coupled together via abus or any suitable interconnection architecture 414.

The processor device 402 may be implemented or performed with a generalpurpose processor, a content addressable memory, a digital signalprocessor, an application specific integrated circuit, a fieldprogrammable gate array, any suitable programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination designed to perform the functions described here. Moreover,the processor device 402 may be implemented as a combination ofcomputing devices, e.g., a combination of a digital signal processor anda microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a digital signal processor core, orany other such configuration.

The memory 404 may be realized as RAM memory, flash memory, EPROMmemory, EEPROM memory, registers, a hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. In thisregard, the memory 404 can be coupled to the processor device 402 suchthat the processor device 402 can read information from, and writeinformation to, the memory 404. In the alternative, the memory 404 maybe integral to the processor device 402. As an example, the processordevice 402 and the memory 404 may reside in an ASIC. At least a portionof the memory 404 can be realized as a computer storage medium that isoperatively associated with the processor device 402, e.g., a tangiblecomputer-readable medium having computer-executable instructions storedthereon. The computer-executable instructions, when read and executed bythe processor device 402, cause the device 400 to perform certain tasks,operations, functions, and processes that are specific to the particularembodiment. In this regard, the memory 404 may represent one suitableimplementation of such computer-readable media. Alternatively oradditionally, the device 400 could receive and cooperate withcomputer-readable media (not separately shown) that is realized as aportable or mobile component or platform, e.g., a portable hard drive, aUSB flash drive, an optical disc, or the like.

The device-specific hardware, software, firmware, UI, and features 406may vary from one embodiment of the device 400 to another. For example,the device-specific hardware, software, firmware, UI, and features 406will support: medical device operations when the device 400 is realizedas a medical device (e.g., an insulin infusion pump); smartphonefeatures and functionality when the device 400 is realized as asmartphone; sensor operations and features when the device 400 isrealized as an analyte sensor; etc. In practice, certain portions oraspects of the device-specific hardware, software, firmware, UI, andfeatures 406 may be implemented in one or more of the other blocksdepicted in FIG. 4.

If present, the UI of the device 400 may include or cooperate withvarious features to allow a user to interact with the device 400.Accordingly, the UI may include various human-to-machine interfaces,e.g., a keypad, keys, a keyboard, buttons, switches, knobs, a touchpad,a joystick, a pointing device, a virtual writing tablet, a touch screen,a microphone, or any device, component, or function that enables theuser to select options, input information, or otherwise control theoperation of the device 400. The UI may include one or more graphicaluser interface (GUI) control elements that enable a user to manipulateor otherwise interact with an application via the display element 412.

The communication module 410 facilitates data communication between thedevice 400 and other components as needed during the operation of thedevice 400. In the context of this description, the communication module410 can be employed to transmit or stream device-related control data,patient-related data, device-related status or operational data, therapyrecommendations, infusion device adjustment recommendations and relatedcontrol instructions, and the like. It should be appreciated that theparticular configuration and functionality of the communication module410 can vary depending on the hardware platform and specificimplementation of the device 400. Accordingly, with reference to FIG. 1,the communication module of the intermediary device 112 can be utilizedto receive and transmit sensor data. Moreover, the communication moduleof the medical device 104 can be used to receive sensor data from anactive analyte sensor device 108, 110. In practice, an embodiment of thedevice 400 may support wireless data communication and/or wired datacommunication, using various data communication protocols. For example,the communication module 410 could support one or more wireless datacommunication protocols, techniques, or methodologies, including,without limitation: RF; IrDA (infrared); Bluetooth; Bluetooth Low Energy(BLE); ZigBee (and other variants of the IEEE 802.15 protocol); IEEE802.11 (any variation); IEEE 802.16 (WiMAX or any other variation);Direct Sequence Spread Spectrum; Frequency Hopping Spread Spectrum;cellular/wireless/cordless telecommunication protocols; wireless homenetwork communication protocols; paging network protocols; magneticinduction; satellite data communication protocols; wireless hospital orhealth care facility network protocols such as those operating in theWMTS bands; GPRS; and proprietary wireless data communication protocolssuch as variants of Wireless USB. Moreover, the communication module 410could support one or more wired/cabled data communication protocols,including, without limitation: Ethernet; powerline; home networkcommunication protocols; USB; IEEE 1394 (Firewire); hospital networkcommunication protocols; and proprietary data communication protocols.

The display element 412 is suitably configured to enable the device 400to render and display various screens, recommendation messages,notifications, GUIs, GUI control elements, drop down menus, auto-fillfields, text entry fields, message fields, or the like. Of course, thedisplay element 412 may also be utilized for the display of otherinformation during the operation of the device 400, as is wellunderstood. Notably, the specific configuration, operatingcharacteristics, size, resolution, and functionality of the displayelement 412 can vary depending upon the practical implementation of thedevice 400.

The disclosed subject matter relates to a system and related operatingmethodology for initializing, configuring, and/or calibrating an analytesensor device (such as a continuous glucose sensor) based on sensor datafrom a previously deployed sensor device of the same type. Continuousglucose monitoring sensors require blood glucose measurements (samples)for calibration. However, fingerstick blood glucose measurements can beunpleasant and burdensome to patients. Disposable glucose sensor devicesallow patients to receive uninterrupted sensor glucose data by way of“sensor overlap” during which the patient deploys a new sensor andallows it to initialize and warm up while an existing sensor is stillactively providing valid sensor glucose data. The methodology presentedhere leverages sensor data from the old sensor device for purposes ofcalibrating and configuring the new sensor device. During the sensoroverlap period, the currently deployed (old) sensor provides sensor datathat is received by the new sensor. The disclosed system may use anintermediary communication device to facilitate the transfer of sensordata, or it may use direct communication between the two sensor devices.The new sensor device uses the received sensor data to perform initialcalibration and/or configuration of sensor operating parameters withoutrequiring a new blood glucose sample.

The disclosed methodology improves the experience of the patient byreducing the number of fingerstick measurements and by reducing theamount of patient interaction required to activate a newly deployedsensor. Moreover, the disclosed methodology reduces the time a user iswithout therapy. As explained in more detail below, the user willreceive uninterrupted sensor readings and can therefore remain in anautomatic (closed loop therapy) operating mode while a new sensor isdeployed.

The disclosed system and methodologies can also be used to transfersensor data for use with features and operations other than sensorcalibration. For example, the received sensor data can be used to reducethe duration of sensor initialization or warmup, improve sensor accuracyand characterization of the user, and detect out-of-box inconsistenciesor inaccuracies of newly deployed sensors. In certain implementations,the disclosed subject matter is applicable to continuous glucose sensorenabled insulin infusion pump systems and standalone continuous glucosemonitoring systems. Moreover, the disclosed subject matter can also beutilized with any suitably configured medical device system thatincludes or cooperates with disposable sensor devices.

FIG. 5 is a flow chart that illustrates an exemplary embodiment of asensor initializing and calibration process 500. The various tasksperformed in connection with process 500 may be performed by software,hardware, firmware, or any combination thereof. For illustrativepurposes, the following description of process 500 may refer to elementsmentioned above in connection with FIGS. 1-4. In practice, portions ofprocess 500 may be performed by different elements of the describedsystem, e.g., a sensor device, a medical device, an intermediary device,a smartphone app, or the like. It should be appreciated that process 500may include any number of additional or alternative tasks, the tasksshown in FIG. 5 need not be performed in the illustrated order, andprocess 500 may be incorporated into a more comprehensive procedure orprocess having additional functionality not described in detail herein.Moreover, one or more of the tasks shown in FIG. 5 could be omitted froman embodiment of the process 500 as long as the intended overallfunctionality remains intact.

The process 500 assumes that a first (old) analyte sensor device isoperating while deployed at the user (task 502). More specifically, theold analyte sensor device is operating in a measurement mode to generatecorresponding sensor signals that are indicative of an analyte level ofthe user. While operating in the measurement mode, the sensor signalsgenerated by the old analyte sensor device can be saved at the oldanalyte sensor device, transmitted to a medical device, transmitted toan intermediary device, uploaded to a cloud-based computing device, orthe like.

The process 500 continues by deploying a second (new) analyte sensordevice to measure the analyte level of the user (task 504). For thisexample, the new analyte sensor device is deployed onto the body of theuser by way of an insertion component using conventional insertiontechniques. The new analyte sensor is deployed and prepared for usagewhile the old analyte sensor device remains operating in the measurementmode. In connection with deployment of the new analyte sensor, theprocess 500 pairs the new analyte sensor device with the intermediarydevice and/or with the medical device (task 506), and activates aninitialization mode of the new analyte sensor (task 508). Pairing of thenew analyte sensor device establishes a secure data communication linkto facilitate transmission of sensor configuration data from theintermediary device to the new analyte sensor device, and to facilitatetransmission of sensor data from the new analyte sensor device to theintermediary device if so desired.

The process 500 concurrently operates both analyte sensor devices duringan “overlap” period (task 510). The concurrent overlap periodcorresponds to operation of the old analyte sensor device in itsmeasurement mode, along with operation of the new analyte sensor in itsinitialization mode or following the initialization mode. After the newanalyte sensor device enters the initialization mode, it can communicateits “warm-up” status to a destination device, such as the intermediarydevice. The intermediary device can respond to the communicated statusby requesting information from the old analyte sensor device. Thus,during this concurrent overlap period, the new analyte sensor devicereceives sensor configuration data that was generated by the old analytesensor device (task 512). For the exemplary embodiment presented here,the new analyte sensor device receives the sensor configuration dataindirectly, via the intermediary device (which may serve as a datapassthrough component in this context). In other embodiments, however,the new analyte sensor device receives the sensor configuration datadirectly from the old analyte sensor device, in accordance with a securepoint-to-point data communication protocol. Thus, the sensorconfiguration data originating at the old analyte sensor device istransferred to the new analyte sensor device for processing, handling,and storage as needed.

The configuration/calibration data provided by the old analyte sensordevice may include any of the following information, without limitation:

One or more prior measurement samples and their age in relation to acalibration transfer time (absolute time (UTC), device (CGM or pump)reference time, or the like). Calibration transfer time is defined asthe time at which the calibration data is retrieved from the old sensordevice. In some embodiments, the data must be retrieved from the oldsensor device and written to the new sensor device within a fixed orpredetermined window of valid time. The timing data is not adjusted tocompensate for the time elapsed between these events. In otherembodiments, a display device may adjust the timing information of eachsample to compensate for an extended period of elapsed time between thetwo data exchange events (retrieval from the old sensor device andtransmission to the new sensor device).

One or more prior measurement samples and their age in relation to asensor reference time (sensor start time or other epoch known only tothe old sensor device). The data retrieved may also include thecalibration transfer time in relation to the sensor reference time. Insome embodiments, the data must be retrieved from the old sensor deviceand written to the new sensor device within a fixed or predeterminedwindow of valid time. The timing data is not adjusted to compensate forthe time elapsed between these events. In other embodiments, a displaydevice may adjust the calibration transfer time information or thetiming information of each sample to compensate for an extended periodof elapsed time between the two data exchange events (retrieval from theold sensor device and transmission to the new sensor device).

One or more prior measurement samples with absolute timestamps. Thesetimestamps may be in a time scale maintained by the display device, or aglobal time reference (UTC, Unix epoch time, etc.).

One or more prior measurement samples with no timing information.

One or more prior measurement samples with predetermined time separation(e.g., an array of measurements at 30-minute intervals).

Additional context, status, or device health data.

The measurement samples may include any of the following, withoutlimitation: glucose concentrations derived from blood; glucoseconcentrations derived from interstitial fluid; glucose concentrationrate-of-change data; sensor current values; sensor electrode voltages;EIS results; other state data from the sensor device.

Referring again to FIG. 5, during operation of the new analyte sensordevice in its initialization mode, and concurrently with operation ofthe old analyte sensor device in its measurement mode, the process 500continues by configuring at least one sensor parameter of the newanalyte sensor device (task 514). Configuring the new analyte sensordevice is based on at least some of the received sensor configurationdata. In this context, the received sensor configuration data is used toadjust settings, modify control algorithms or adjust algorithm constantsor factors, adjust preferences, and/or adjust certain variables thataffect the performance, output, or operation of the new analyte sensordevice. For the exemplary embodiment described here, the configuringperformed at task 514 includes calibration of the new analyte sensordevice using at least some of the received sensor configuration data.

In certain embodiments, the new analyte sensor device reviews thereceived sensor configuration data to determine whether or not the datacan be used for calibration. If the received data is suitable forcalibration, then sensor calibration proceeds with the received data. Ifthe new analyte sensor device determines that the received data isdeficient, is otherwise unsuitable for use with calibration, or shouldbe supplemented, then it can generate an indication or message to promptcalibration in accordance with conventional methodologies (e.g., obtainan analyte sample from the user). Checking the received sensorconfiguration data may involve the application of validity tests to thedata or its associated metadata, such as timestamps. In practice, thedetermination can be related to the specific sensor algorithm. Forexample, the algorithm may do a calibration error check to review an oldsensor glucose sample divided by the sensor current signal (commonlyreferred to as ISIG) to determine whether the ratio is within certainbounds. It can also compare this ratio to other known ratios (e.g., forprevious sensors). It can also look to see if the ISIG after calibrationis above/below a certain range. These and other techniques can beutilized for this feature.

At the outset, the process 500 assumes that the two sensors generatemeasurements that are within a practical working tolerance of eachother, e.g., less than a 10% difference. Consequently, the new sensordevice can be initially trusted for purposes of therapy decisions.Moreover, the existing sensor data generated by the old sensor devicecan be taken as an accurate measurement of the analyte level ofinterest, such that the new sensor device can be calibrated based on theexisting sensor data (rather than based on a new sample from the user).Over time, the new sensor device can be calibrated on its own based onanalyte samples taken from the user, but the initial calibration can beseamlessly performed with no delay and with little to no userinvolvement.

In certain embodiments, the new analyte sensor device updates its statusto indicate completion of the configuration/calibration procedure. Aftercompletion of the configuration/calibration, the process 500 continuesby transitioning operation of the new analyte sensor device from itsinitialization mode to its measurement mode (task 516), during which thenew analyte sensor device generates sensor signals that are indicativeof the measured analyte level (e.g., blood glucose) of the user. Therecan be various manual or automatic triggers to activate the switch fromthe old to the new sensor device. For example, the old sensor deviceexpires, the user initiates a change in the sensors, or a time-basedtrigger can be implemented. Notably, the generated sensor signals willalready be calibrated to some extent, and ongoing operation of the newanalyte sensor device in its measurement mode can include furthercalibration based on analyte samples obtained from the user, such asfingerstick blood glucose measurements. After transitioning to themeasurement mode of the new analyte sensor device, operation of the oldanalyte sensor device can be terminated (task 518). Task 518 may beautomatically controlled by one or both of the sensor devices, by thelinked medical device, and/or by the linked intermediary device.Alternatively, task 518 may be automatically performed when the oldanalyte sensor device is removed from the body of the user, when itbecomes unpaired from the intermediary device, when it loses dataconnectivity with the new analyte sensor device, or the like.Thereafter, only the new analyte sensor device remains deployed,operating in its normal measurement mode. In the context of an insulininfusion system that includes a continuous glucose sensor, the process500 allows a new sensor device to be quickly and convenientlyinitialized without requiring a blood sample, and in a way that does notresult in suspension of the insulin infusion pump operation orsuspension of certain operations, such as automatic closed loop control.

Although sensor calibration is described above, the system 100 and theprocess 500 can be utilized for other purposes with sensor devices thatdo not require user calibration, e.g., factory-calibrated sensordevices. In this regard, the transfer of sensor data between two sensordevices can be used to enhance sensing accuracy, reduce warm-up time, orotherwise improve sensor device performance even if the sensor devicerequires no calibration.

As explained above, the system 100 and the process 500 support differentpossible device topologies and arrangements. In accordance with theexemplary embodiment, an intermediary device with a display functions asthe communication path for the two sensor devices, while alsofunctioning as the primary display and user interface for the user. Inan alternative implementation, an intermediary device merely serves as adisplay/interface device for the user, while the two sensor devicescommunicate directly with each other. In another embodiment, the system100 need not include a display device or an intermediary device. In suchan embodiment, the two sensor devices communicate directly with eachother. It should be appreciated that other configurations and topologiescan also be deployed with the system 100 if so desired.

Data Integrity

The configuration/calibration data may be transmitted in an unencryptedmanner, e.g., as plaintext. Alternatively, the configuration/calibrationdata can be partially or fully encrypted to protect the data againstinterception from unauthorized parties. Some possible implementationsinclude the following, without limitation:

The old sensor device provides a block of data to the display devicethat is encrypted using a first encryption key known to the old sensordevice and the display device. The display device decrypts the data uponreception. The display device may re-encrypt the data with a secondencryption key known to the display device and the new sensor deviceprior to transmission to the new sensor device. The new sensor devicedecrypts the data upon reception.

The old sensor device provides a block of data encrypted with a key notknown to the display device, but known to the new sensor device. Thedisplay device transfers the encrypted data to the new sensor device.The new sensor device decrypts the data upon reception. This embodimentmay prevent the display device from inspecting or altering the contentsof the sensor-provided data.

The old sensor device directly transmits a block of data to the newsensor device. The data is encrypted with a key known to both of thesensor devices.

The configuration/calibration data may include checksums or hashes toprotect the data against corruption. The configuration/calibration datamay include cryptographic signatures to protect the data againsttampering. Signatures may be computed using symmetric-key or public-keycryptosystems. The calibration data may include validity timestamps toallow the display device or the new sensor device to reject data thatexceeds an age limit.

Automated Wireless Pairing

As explained above, a wireless transmitter may be required to sendreadings from a glucose sensor to an insulin pump or smartphone (e.g.,using the BLUETOOTH wireless data communication standard). Thetransmitter is paired with the pump or smartphone via user input. Inaccordance with conventional designs, the RF transmitters mechanicallyattach to the glucose sensor. When the sensor expires (e.g., in one ortwo weeks), the RF transmitter is mechanically attached to the newsensor. According to modern sensor designs, RF transmitters are builtinside the glucose sensor, yielding benefits associated with a smallerform factor. When the sensor expires, the user must unpair the RFtransmitter from the pump (or smartphone) and pair the new RFtransmitter before starting use of a new sensor.

In certain practical implementations, the user must first unpair the RFtransmitter from the pump. Next, the user can pair a new transmitter.Once the RF pairing is complete, the user can initialize and calibratethe new sensor. This step can take up to two hours. This weekly (orbiweekly) pairing process adds to the already burdensome process ofmaintaining glucose control while switching to a new sensor. Thesemandatory steps can yield hours without sensor protection fromhypoglycemia (e.g., “Suspend on Low” technology) and the pump cannotprovide closed loop therapy without a calibrated sensor. Thus, having anRF transmitter disposed with every glucose sensor may not be a benefitto the user under these circumstances.

Given that RF transmitters and glucose sensors can be implemented withthe same disposable device, a secure and seamless sensor managementscheme is proposed. This produces less user burden than currentproducts, more protection from hypoglycemia, and data collection forsensor quality control. The proposed methodology employs device keymanagement by software, and assumes that the insulin pump (orsmartphone) has a linked user account (e.g., an account suitable for usewith patient status monitoring or recordkeeping).

Feature 1: When the user account orders new sensors, the factoryprovides the shipped sensors' serial numbers to a secure account server.This secure server generates encrypted keys for each serial number, andprovides them to the linked insulin pump (or smartphone). In thisregard, FIG. 6 is a block diagram that illustrates a device keymanagement scheme 600. For this example, the user 602 or user accountgenerates a request 603 or order for new sensors by contacting a helpline 604. The request 603, which may include a user or accountidentifier, is forwarded to a shipping center 606. The shipping center606 provides the serial numbers 608 of the shipped sensor devices (alongwith the user/account identifier) to a secure account server 610. Theserver 610 responds by sending encrypted authorization keys for eachsensor device to the insulin pump or smartphone 612 that is linked tothe user/account identifier.

Feature 2: When the new sensor device is attached to the user's body itenters a “search mode” by broadcasting its serial number in an encryptedformat. Only the device with the preassigned matching keys can replysuccessfully, ending the search mode. This adds the security requiredfor pairing the new sensor device with another device without userinvolvement.

Feature 3: The newly paired sensor silently begins warm-up and does notrequest calibration unless the previous sensor has expired. Thus, thenew sensor is deployed while the old sensor remains active, and bothsensors operate in an “overlapping” manner during a period of time.Should the user provide a blood glucose value, this calibrates the newsensor. Upon successful calibration of the new sensor, the user isinformed that they can remove the old sensor. In practice, the user canbe notified via a single displayed screen or message on the infusionpump or monitoring device. In contrast, the conventional routine forreplacing an old glucose sensor device might require extensive patientinvolvement and interaction with many different display screens.

Feature 4: Enhanced protection from low glucose state during sensorreplacement. Given the new sensor is inserted before the previous sensorexpires, the insulin pump (or smartphone) shares the old sensor'sglucose values with the new sensor. These shared glucose values are usedfor pre-calibration, a sufficient state for providing low glucosedetection from the new sensor (should the old sensor expire). Thus, ifthe user is sleeping, they can still be alerted in response to adetected low glucose condition, and the insulin pump can continue toprovide automated suspend therapy. The sensor glucose values for thepre-calibrated sensor will not be shown to the user. If a fingerstickblood sugar value is provided to the pump (or smartphone), that valuecan be given to the new sensor for fast calibration. In this regard,FIG. 7 is a block diagram that illustrates a sensor pre-calibrationscheme 700. The old sensor device 702 sends its glucose values 703 tothe insulin pump or smartphone 704, which forwards the glucose values703 to the new sensor device 706 for use as pre-calibration values. Thenew sensor device 706 calibrates itself using the glucose values 703 andgenerates its own glucose values 708 that are suitable for use by theinsulin pump or smartphone 704 to provide low protection during a periodof time following deployment of the new sensor device 706. Thus, even ifthe old sensor device 702 expires, the new sensor device 706 can providesufficient low glucose protection using the pre-calibration scheme.

Feature 5: The keys provided to the insulin pump (or smartphone) foreach sensor also include the sensor's manufacturing date and location.If the user inserts a sensor that is too old (shelf life expired), awarning is given to the user. When each sensor expires (or is otherwiseready for replacement) the reason “code” is saved to history (e.g., theuser's account history). As a result, the parent company has thefollowing quality control information: sensor serial number,manufacturing date, and manufacturing location; sensor start date;sensor performance data; and sensor decommission or replacement reason.

Benefits and Results

Continuous Glucose Monitoring (CGM) can be truly continuous: glucosealerts, and low glucose suspends remain active. There is no downtime fordevice removal, un-pairing, new device pairing, starting sensor, warmup(which usually might take up to 2 hours) and calibration (which usuallymight take up to 12 minutes). This also provides more time in automaticglucose control modes (with potentially improved outcomes).

The user can attach a new sensor at bedtime and trust that a “suspendbefore low” function can utilize both the expiring sensor and the newsensor.

Data collection is automated for end-to-end quality control of thesensor.

The automated sensor changeover eliminates a significant amount of useractivity from occurring every 1-2 weeks. These changes significantlyreduce time-on-task and burden.

Device Roles

In some embodiments, the display device acts as a data pass-throughdevice. It does not include logic for determining the efficacy of thecalibration data. The new sensor device determines whether thecalibration data is satisfactory for use in calibrating the new sensordevice. In other embodiments, the display device may check the validityof the calibration data payload or augment it with additionalinformation, such as data generated or maintained by the medical device,status data, or the like. In other embodiments, no display device ispresent in the system 100.

Mechanisms of Data Transfer

The configuration/calibration data may be transferred via a wirelessnetwork, such as a BLUETOOTH network link, Wi-Fi, or another technology.The data may also be transferred through other means of wired orwireless communication. The data may be relayed through a display deviceor transferred directly between two sensors. It may also be relayed viatwo different display or intermediary devices (for example, when apatient is using one sensor device with an insulin infusion pump andwishes to change to a second sensor device monitored by a smartphone).

Other Applications

The data transfer mechanisms and workflows described herein may beemployed in CGM systems not requiring the end user to providecalibration data (“factory calibrated”). For these systems, the datatransferred may instead be used to improve the performance of the newsensor device. Possible applications include the following, withoutlimitation: reducing the duration of the warmup period for the newsensor device; improving the accuracy of initial sensor measurementsfrom the new sensor device; early detection of problems or performanceissues with the old sensor device.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the claimed subjectmatter in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the described embodiment or embodiments. It should beunderstood that various changes can be made in the function andarrangement of elements without departing from the scope defined by theclaims, which includes known equivalents and foreseeable equivalents atthe time of filing this patent application.

What is claimed is:
 1. A method of automatically initializing an analytesensor for a user, the method comprising the steps of: operating a firstanalyte sensor in a first measurement mode to generate first sensorsignals indicative of an analyte level of the user; deploying a secondanalyte sensor to measure the analyte level of the user; operating thesecond analyte sensor in an initialization mode, concurrently withoperation of the first analyte sensor in the first measurement mode, toreceive sensor configuration data generated by the first analyte sensor;during operation of the second analyte sensor in the initializationmode, calibrating the second analyte sensor with at least some of thereceived sensor configuration data; and after the calibrating,transitioning operation of the second analyte sensor from theinitialization mode to a second measurement mode during which the secondanalyte sensor generates second sensor signals indicative of the analytelevel of the user.
 2. The method of claim 1, wherein the second analytesensor receives the sensor configuration data directly from the firstanalyte sensor.
 3. The method of claim 1, wherein the second analytesensor receives the sensor configuration data from an intermediarydevice that communicates with the second analyte sensor.
 4. The methodof claim 3, wherein the intermediary device comprises a medicationinfusion device configured to regulate delivery of medication to theuser based on the sensor signals.
 5. The method of claim 3, wherein theintermediary device comprises a mobile computing device.
 6. The methodof claim 3, further comprising the step of pairing the second analytesensor with the intermediary device to facilitate transmission of thesensor configuration data from the intermediary device to the secondanalyte sensor.
 7. An analyte sensor device comprising: a housing; anelectronics assembly inside the housing; and a sensor element extendingfrom the housing and electrically coupled to the electronics assembly,wherein the sensor element provides sensor signals indicative of ananalyte level of a user when the analyte sensor device is deployed atthe user; the electronics assembly comprising at least one processordevice and non-transitory processor-readable media operativelyassociated with the at least one processor device, theprocessor-readable media comprising executable instructions configurableto cause the at least one processor device to perform a methodcomprising the steps of: activating an initialization mode of theanalyte sensor device; during operation of the analyte sensor device inthe initialization mode, receiving sensor configuration data forprocessing by the electronics assembly, the sensor configuration dataoriginating at a second analyte sensor device deployed at, or previouslydeployed at, the user; during operation of the analyte sensor device inthe initialization mode, configuring at least one sensor parameter ofthe analyte sensor device, based on the received sensor configurationdata; and after the configuring, transitioning operation of the analytesensor device from the initialization mode to a measurement mode duringwhich the analyte sensor device generates sensor signals indicative ofthe analyte level of the user.
 8. The analyte sensor device of claim 7,wherein: activating the initialization mode of the analyte sensor deviceis performed while the old analyte sensor device is deployed at theuser, and while the old analyte sensor device is operating in a secondmeasurement mode during which the old analyte sensor device generatessecond sensor signals indicative of the analyte level of the user; andoperation of the analyte sensor device in the initialization mode isperformed concurrently with operation of the old analyte sensor devicein the second measurement mode.
 9. The analyte sensor device of claim 7,wherein the configuring comprises calibrating the analyte sensor deviceusing at least some of the received sensor configuration data.
 10. Theanalyte sensor device of claim 7, wherein the analyte sensor devicereceives the sensor configuration data directly from the old analytesensor device, or indirectly from an intermediary device thatcommunicates with the analyte sensor device.
 11. A method ofautomatically initializing an analyte sensor for a user, the methodcomprising the steps of: activating a new analyte sensor to measure ananalyte level of the user; during operation of the new analyte sensor inan initialization mode, receiving sensor configuration data at the newanalyte sensor, the sensor configuration data originating at an oldanalyte sensor deployed at, or previously deployed at, the user; duringoperation of the new analyte sensor in the initialization mode,configuring at least one sensor parameter of the new analyte sensor,based on the received sensor configuration data; and after theconfiguring, transitioning operation of the new analyte sensor from theinitialization mode to a first measurement mode during which the newanalyte sensor generates first sensor signals indicative of the analytelevel of the user.
 12. The method of claim 11, wherein activating thenew analyte sensor is performed while the old analyte sensor is deployedat the user and operating in a second measurement mode during which theold analyte sensor generates second sensor signals indicative of theanalyte level of the user.
 13. The method of claim 12, wherein operationof the new analyte sensor in the initialization mode is performedconcurrently with operation of the old analyte sensor in the secondmeasurement mode.
 14. The method of claim 12, wherein the new analytesensor receives the sensor configuration data directly from the oldanalyte sensor.
 15. The method of claim 11, wherein the new analytesensor receives the sensor configuration data from an intermediarydevice that communicates with the new analyte sensor.
 16. The method ofclaim 15, wherein the intermediary device comprises a medical deviceconfigured to regulate administration of therapy to the user based onthe first sensor signals.
 17. The method of claim 15, wherein theintermediary device comprises a mobile computing device.
 18. The methodof claim 15, further comprising the step of pairing the new analytesensor with the intermediary device to facilitate transmission of thesensor configuration data from the intermediary device to the newanalyte sensor.
 19. The method of claim 11, further comprising the stepof terminating operation of the old analyte sensor, the terminatingoccurring after the transitioning operation of the new analyte sensor tothe first measurement mode.
 20. The method of claim 11, wherein theconfiguring step comprises calibrating the new analyte sensor using atleast some of the received sensor configuration data.